Biomolecular motors are considered promising materials for constructing biological actuators. In general, biomolecular actuators are driven by the conversion of adenosine triphosphate (ATP) to drive their movement. These actuators can be used in nanoscale mechanical devices to pump fluids, open and close valves, and provide translational movement of cargo. The difficulty lies in how to integrate these sophisticated functions to do specific tasks. A cell-based biological machine is a set of sub-components comprising living cells and cell-instructive micro-environments that interact to perform a prescribed task. Functions of biological machines include sensing, information processing, actuation, protein expression, and transportation.
There has been substantial interest in the fabrication of biological machines. Most cell-based biohybrid actuators have been limited to rigid materials such as silicon and polydimethylsiloxane (Kim et al., 2007, Lap Chip 7:1504-8; Feinberg et al., 2007, Science 317: 1366-70.) Hydrogels, which are cross-linked polymer networks that are hydrated and possess tissue-like elasticity, are a useful class of compounds for biological applications (Drury & Mooney, 2003, Biomaterials, 24:4337-51; Slaughter et al., 2009, Adv. Mater. 21:3307-29). Many biocompatible hydrogels with varying structures and properties have been identified in nature or developed in the lab.
There remains a need to develop controllable, soft robotic devices with bidirectional locomotive capabilities that can dynamically sense and respond to a range of complex environmental signals. There also remains the need to develop methods for fabricating such robotic devices with short fabrication time, the potential for scalability, and spatial control.